JUN and melanoma: In parallel to NF-κB, the JNK/AP1 signaling pathway is commonly induced by TNFα, as shown in our previous studies.44 Immunoblotting showed that phosphorylation of c-Jun (pc-Jun), a predominant AP1 subunit,52 was readily detectable in control melanoma cells, and markedly reduced in shMALT1 cells (Figure 4a).